Packing



H. R. FRY

:PACKING Dec. 28, 1943.

' Filed Dec. 10, 1941 I-Ie NR5 IINYENTOR BY r 1 477'}: I

latented Dec. 28, 1943 I 1 Claim.

This invention relates to packing for general hydraulic service inpumps, elevator plungers, rams, accumulators, and equipment handlin morespecifically, relates to a packing comprising continuous artificialcellulosic filaments.

cold water, from fiax'and cottonfibers. Flax fibers ranging in lengthfrom five to forty inches and short cotton fibers have been spun, drawn,and twisted to give a roving. Rovings of a suitable size have then beenbraided into a packing. his packing has been impregnated with alubricant such a tallow before installation in the ump. In some cases,the roving hasbeen imregnated with the lubricant before the braidingoperation.

Packing constructed from rovings of flax or cotton fibers ofcomparatively hort lengths has een objectionable in a number of cases.The

urface of the packing and provid resistance to the movement of the pumppart over the surface f the packing. Th comparatively short fiberrovings which made up the braided packing have been known to pull apart,thus requiring repacking of the pump. Also, packings from short fibersfrequently have not held up 'well under high pressures. Flaxdeteriorates quickly'in the presence of acid and basic solutions, eventhough these solutions be dilute.

It is, therefore, an object of the present invention to provide animproved packing for pumps, etc. It is another object of this inventionto provide a packing which exhibits a minimum of resistance to themoving parts of the pump in contact therewith. 4

Other objects of this invention will appear hereinafter.

The objects.. pf the present invention are accomplished, ingeneral, byconstructing packing from one or more ropes or bundles of continuousartificial filaments.

Forconvenience, this invention will be described in terms of a tow orrope of continuous regenerated cellulose filaments produced fromviscose, a1-

hough other artificial cellulosic materials may lso be used, forexample, continuous regenerated ellulose filaments produced by thecupramfresh and salt water, and brine. The invention,

. UNITED STATES PATENT OFFICE PACKING Henry Russel Fry, Bridgevllle,Del., assignor to E. L du Pont de Nemours & Company, Wilmington, Del., acorporation of Delaware Application December 10, 1941, Serial No.422,397

It has been customary heretofore to construct l packing, particularlyfor pumps handling hot and description, when taken in connection withthe accompanying illustration, in which;

Figure 1 is a perspective view of a braided packing constructed ofcontinuous artificial cellulosic filaments.

Figure'2 is a perspective view of a twisted pack ing constructed ofsimilar continuous filaments.

Referring to Figure 1 of the drawing, reference numeral 10 designates abraidedpacking comprising a plurality of ropes or bundles l2 ofcontinuous artificial cellulosic filaments.

In Figure 2, numeral l4 designates a twisted strand structure comprisinga plurality of bundles iii of continuous artificial cellulosicfilaments.

In accordance with the preferred practice of the present invention, aplurality of ropes or bundles of substantially parallel, continuousartificial cellulosic filaments is braided together in the conventionalpacking braiding equipment and any fiber ends'protrude to some extent onthe I the resulting braided product impregnated with a lubricant such astallow. The resulting product may have a square, round, or othercross-section depending 'upon the particular braiding process.

. used. Alternatively, the braided product may be Y the braidedcontinuous filament cellulosic ropes is then ready for cutting to thedesired lengths for incorporation in the packing gland of equipmentrequiring the use of such packing.

It has been found that bundles or ropes of continuous filaments spun bythe well-known processes from viscose are suitable for use in accordancewith the present invention. The bundle or rope as used herein consistsof a lar e ber of continuous filaments brought together in one bundle.The bundle of filaments may be twisted or not as desired. It has beenfound further that special yarns such as the high tenacity yarnsdescribed in U. S. Patent No. 2,133,714 and the permanently crimpedyarns described in US. Patent No. 2,249,745 are also suitable. In somecases,

'bundles or ropes composed'of crimped filaments are preferred because oftheir high resilience.

The following specific examples will more Eight ropes, each of whichconsists of 5300 continuous, 1 /2 denier, regenerated cellulosefilaments, are braided to ether on a standard braiding machine. Thebraided product is impregnated with tallow and pressed to give it asquare cross-section. This material is used in packing a pump withexcellent results.

Example II Example III Eight ropes, each comprised of 10,000 fiber Dfilaments, are braided in a, conventional rope braiding machine. Thebraided rope is impregnated with tailow to produce a packing. Theresulting packing showed long life as a packing for pumps handling warmor cold water. Packing constructed with fiber D filaments is veryresilient and is of particular utility when a packing of high resilienceis in demand.

New, crimped, wool-like regenerated cellulose fibers, filaments, andyarns and processes for producing the same are described and claimed inU. S. Patent No. 2,249,745. The process, as defined in said patent,comprises generally the extrusion of viscose into a coagulating bathhaving a rapid coagulating action and a slow, or no, regenerating actionwith a velocity of extrusion at least four times the velocity ofdraw-oil. The streams of viscose issuing from the spinneret into thecoagulating bath under the aforementioned conditions spontaneouslyassume a finely crimped form which persists as a permanent structuralcharacteristic in the filaments.

The resulting yarn is CmpoSed of substantially non-crenulated filamentshaving an inherent and substantially permanent crimp, the crimps in theseveral filaments of the yarn being out of phase with each other. Thefilaments exhibit substantially no orientation in the direction of thefiber axis.

For purposes of convenience and ready identification, this yarn willhereinafter -be referred to as fiber D" yarn. Packing produced from arope of continuous regenerated cellulose filaments may be impregnatedwith any of the known lubricants used in the pump packing art. Thesewill include greases, tallow, and tallow combined with other materialssuch as high melting waxes. 'ihe lubricants may further containgraphite. The lubricant may be applied to the rope either before orafter braiding.

The filaments comprising the rope may vary in denier from 1 to 30 andhigher. if desired. The rope may contain any desired number of filamentsdepending upon the size of packing to be produced. A rope consisting01'1300 regenerated cellulose filaments of 20 denier per filament I andhaving a twist of 0.57 turn per inch, gave excellent results whenbraided into a pump packing material. The rope may be twisted or nottwisted before the braiding operation according to the degree ofrigidity desired. Since the rayon rope is made up of continuousfilaments, twisting is not required for strength.

The pump packing of the present invention has the advantage that thecontinuous filaments have a slick smooth surface thereby setting up lessfriction with the moving part of the pump and requiring less power todrive the said moving parts in contact with the packing. The smoothsurface of the filaments used in this invention has the furtheradvantage that they permit less leakage of the liquid being pumped. Therough irregular surface of previously used fibers permits channelingthrough the packing whereas the artificial cellulosic continuousfilaments of the present invention eliminate such channeling to a largeextent. The continuous filament packing may be used in place of flax orcotton in all installations and may additionally be used satisfactorilyin pumps handling dilute acids and caustic solutions. The packing issatisfactory in all types of pumps including centrifugal or rotary typesand reciprocating types, which operate at high pressures. It may furtherbe used in valve stems, accumulators, elevator plungers, .presses, rams,etc., and on equipment handling cold or warm water, and brine.

A further advantage of theuse of continuous filament cellulosic ropes inthe manufacture of packing material is the uniformity with which thepacking can be made; All the filaments are made the samesize and therope is uniform. No thick or thin portions will be present which willproduce irregularities in the finished packing. Protruding or enlargedportions on a packing will wear to give a large number of broken ends.

These ends are abrasive and cause wear of the moving parts in contacttherewith.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited to the details described herein except as set forth in theappended claim.

I claim:

A packing comprising a braided structure consisting of a plurality ofropesof continuous, substantially non-crenulated regenerated cellulosefilaments exhibiting substantially no orientation in the'direction ofthe filament axis and having an inherent and substantially permanentcrimp, the crimps in the several filaments being out of phase with eachother.

HENRY RUSSEL FRY.

